Chlamydia Pneumoniae Infection Promotes The Migration Of Vascular Smooth Muscle Cells Through The C-Fos/IL-17C Signaling

Objective:Atherosclerosis is a slowly progressing chronic inflammatory disorder in the arteries.Chlamydia pneumoniae?C.pneumoniae?infection is closely associated with the initiation and development of atherosclerosis.The migration of vascular smooth muscle cell?VSMC?from the medial to intima of the artery is a key step during atherosclerosis.Our previous study showed that C.pneumoniae infection could promote VSMC migration,but the exact molecular mechanisms remain unclear.Recent studies have shown that IL-17C expression could be upregulated by the infections of multiple pathogens,and IL-17C was shown to be involved in cell migration.Our study was to explore the roles of IL-17C in VSMC migration induced by C.pneumoniae infection and the related mechanisms in this process.Methods and Results:Part ?:C.pneumoniae infection promotes VSMC migration possibly through IL-17C.We firstly detected the expression of IL-17C in VSMCs in the atherosclerotic lesion area of the ApoE^-/-mice and rat VSMCs with C.pneumoniae infection;Then,Transwell assay was used to detect the effects of C.pneumoniae infection on VSMC migration after changing the expression of IL-17C.Our results showed that the expression of IL-17C was dramatically increased in VSMCs in the atherosclerotic lesion area of the ApoE^-/-mice and rat VSMCs after C.pneumoniae infection.The migration of VSMC was significantly promoted by the exposure to rIL-17C,and IL-17C-siRNA-mediated knockdown of IL-17C strongly suppressed the infection-induced VSMC migration.These results demonstrate that C.pneumoniae infection promotes VSMC migration possibly through IL-17C.Part ?:C.pneumoniae infection upregulates IL-17C expression through activating c-Fos/ERK signalingThe c-Fos expression and activation in VSMCs in the atherosclerotic lesion area of the ApoE^-/-mice and rat VSMCs with C.pneumoniae infection was detected by immunofluorescence and Western blot;Then,we determined the expression levels of IL-17C when overexpressing c-Fos or inhibiting c-Fos expression and phosphorylation at Ser32 and Thr325;?Chromatin Immunoprecipitation,CHIP?assay was used to observe the binding of c-Fos to the promoters of IL-17C.And ERK phosphorylation was detected by Western blot after C.pneumoniae infection or overexpressing c-Fos.After the pretreatment of VSMCs with PD98059,we detected the expression of IL-17C induced by overexpressing c-Fos.Our data showed that C.pneumoniae infection induced c-Fos expression and activation in VSMCs;IL-17C expression was significantly upregulated by the overexpression of c-Fos,and the increased IL-17C expression caused by the infection was significantly reduced upon the inhibition of c-Fos expression and phosphorylation at Ser32 and Thr325;CHIP results showed that C.pneumoniae infection could not significantly increase the binding of c-Fos to the promoters of IL-17C;ERK phosphorylation was significantly enhanced after C.pneumoniae infection or the overexpression of c-Fos.And after the inhibition of ERK phosphorylation by PD98059,IL-17C expression induced by overexpressing c-Fos was significantly suppressed in VSMCs.Our results suggest that c-Fos regulates the expression of IL-17C in VSMCs induced by C.pneumoniae infection through phosphorylating ERK.Part ?:IL-17C is critical for C.pneumoniae infection-induced c-Fos activation dependent on phosphorylation of ERKFirstly,Western blot was used to detect the expression of c-Fos and the phosphorylation of c-Fos and ERK induced by rIL-17C stimulation.After the pretreatment of VSMCs with PD98059,we detected the expression and activation of c-Fos induced by rIL-17C stimulation.Then,we detected the c-Fos expression and phosphorylation after the depletion of IL-17C by the specific siRNA.Our results showed that IL-17C could lead to the significant increases in c-Fos expression and phosphorylation at Ser32 and Thr325,and in ERK phosphorylation.PD98059 inhibited c-Fos expression and phosphorylation at Ser32 and Thr325 caused by the exposure to rIL-17C;Increased c-Fos expression and phosphorylation at Ser32and Thr325 induced by C.pneumoniae infection could be significantly suppressed after the knockdown of IL-17C.Our data indicates that IL-17C is critical for c-Fos expression and phosphorylation by activating ERK.Conclusion:C.pneumoniae infection promotes VSMC migration through c-Fos/IL-17C pathway.